diff --git a/Backend.Tests/Services/MergeServiceTests.cs b/Backend.Tests/Services/MergeServiceTests.cs
index 2f0580975c..c5373b552f 100644
--- a/Backend.Tests/Services/MergeServiceTests.cs
+++ b/Backend.Tests/Services/MergeServiceTests.cs
@@ -199,8 +199,6 @@ public void UndoMergeMultiChildTest()
         [Test]
         public void AddMergeToBlacklistTest()
         {
-            _ = _mergeBlacklistRepo.DeleteAllSets(ProjId).Result;
-            _ = _mergeGraylistRepo.DeleteAllSets(ProjId).Result;
             var wordIds = new List<string> { "1", "2" };
 
             // Adding to blacklist should clear from graylist
@@ -219,7 +217,6 @@ public void AddMergeToBlacklistTest()
         [Test]
         public void AddMergeToBlacklistErrorTest()
         {
-            _ = _mergeBlacklistRepo.DeleteAllSets(ProjId).Result;
             var wordIds0 = new List<string>();
             var wordIds1 = new List<string> { "1" };
             Assert.That(
@@ -231,7 +228,6 @@ public void AddMergeToBlacklistErrorTest()
         [Test]
         public void IsInMergeBlacklistTest()
         {
-            _ = _mergeBlacklistRepo.DeleteAllSets(ProjId).Result;
             var wordIds = new List<string> { "1", "2", "3" };
             var subWordIds = new List<string> { "3", "2" };
 
@@ -243,7 +239,6 @@ public void IsInMergeBlacklistTest()
         [Test]
         public void IsInMergeBlacklistErrorTest()
         {
-            _ = _mergeBlacklistRepo.DeleteAllSets(ProjId).Result;
             var wordIds0 = new List<string>();
             var wordIds1 = new List<string> { "1" };
             Assert.That(
@@ -298,7 +293,6 @@ public void UpdateMergeBlacklistTest()
         [Test]
         public void AddMergeToGraylistTest()
         {
-            _ = _mergeGraylistRepo.DeleteAllSets(ProjId).Result;
             var wordIds = new List<string> { "1", "2" };
             _ = _mergeService.AddToMergeGraylist(ProjId, UserId, wordIds).Result;
             var graylist = _mergeGraylistRepo.GetAllSets(ProjId).Result;
@@ -307,10 +301,24 @@ public void AddMergeToGraylistTest()
             Assert.That(expectedEntry.ContentEquals(graylist.First()), Is.True);
         }
 
+        [Test]
+        public void AddMergeToGraylistSupersetTest()
+        {
+            var wordIds12 = new List<string> { "1", "2" };
+            var wordIds13 = new List<string> { "1", "3" };
+            var wordIds123 = new List<string> { "1", "2", "3" };
+
+            _ = _mergeService.AddToMergeGraylist(ProjId, UserId, wordIds12).Result;
+            _ = _mergeService.AddToMergeGraylist(ProjId, UserId, wordIds13).Result;
+            Assert.That(_mergeGraylistRepo.GetAllSets(ProjId).Result, Has.Count.EqualTo(2));
+
+            _ = _mergeService.AddToMergeGraylist(ProjId, UserId, wordIds123).Result;
+            Assert.That(_mergeGraylistRepo.GetAllSets(ProjId).Result, Has.Count.EqualTo(1));
+        }
+
         [Test]
         public void AddMergeToGraylistErrorTest()
         {
-            _ = _mergeGraylistRepo.DeleteAllSets(ProjId).Result;
             var wordIds = new List<string>();
             var wordIds1 = new List<string> { "1" };
             Assert.That(
@@ -324,24 +332,28 @@ public void AddMergeToGraylistErrorTest()
         [Test]
         public void RemoveFromMergeGraylistTest()
         {
-            _ = _mergeGraylistRepo.DeleteAllSets(ProjId).Result;
-            var wordIds12 = new List<string> { "1", "2" };
-            var wordIds13 = new List<string> { "1", "3" };
-            _ = _mergeService.AddToMergeGraylist(ProjId, UserId, wordIds12).Result;
-            _ = _mergeService.AddToMergeGraylist(ProjId, UserId, wordIds13).Result;
-            var graylist = _mergeGraylistRepo.GetAllSets(ProjId).Result;
-            Assert.That(graylist, Has.Count.EqualTo(2));
-            var wordIds123 = new List<string> { "1", "2", "3" };
-            var removed = _mergeService.RemoveFromMergeGraylist(ProjId, UserId, wordIds123).Result;
-            Assert.That(removed, Has.Count.EqualTo(2));
-            graylist = _mergeGraylistRepo.GetAllSets(ProjId).Result;
-            Assert.That(graylist, Is.Empty);
+            var wordIds = new List<string> { "1", "2", "3" };
+            _ = _mergeService.AddToMergeGraylist(ProjId, UserId, wordIds).Result;
+            Assert.That(_mergeGraylistRepo.GetAllSets(ProjId).Result, Has.Count.EqualTo(1));
+            Assert.That(_mergeService.RemoveFromMergeGraylist(ProjId, UserId, wordIds).Result, Is.True);
+            Assert.That(_mergeGraylistRepo.GetAllSets(ProjId).Result, Has.Count.EqualTo(0));
+        }
+
+        [Test]
+        public void RemoveFromMergeGraylistSupersetTest()
+        {
+            var wordIds = new List<string> { "1", "2" };
+            _ = _mergeService.AddToMergeGraylist(ProjId, UserId, wordIds).Result;
+            Assert.That(_mergeGraylistRepo.GetAllSets(ProjId).Result, Has.Count.EqualTo(1));
+
+            wordIds.Add("3");
+            Assert.That(_mergeService.RemoveFromMergeGraylist(ProjId, UserId, wordIds).Result, Is.False);
+            Assert.That(_mergeGraylistRepo.GetAllSets(ProjId).Result, Has.Count.EqualTo(1));
         }
 
         [Test]
         public void RemoveFromMergeGraylistErrorTest()
         {
-            _ = _mergeGraylistRepo.DeleteAllSets(ProjId).Result;
             var wordIds = new List<string>();
             var wordIds1 = new List<string> { "1" };
             Assert.That(
@@ -355,7 +367,6 @@ public void RemoveFromMergeGraylistErrorTest()
         [Test]
         public void IsInMergeGraylistTest()
         {
-            _ = _mergeGraylistRepo.DeleteAllSets(ProjId).Result;
             var wordIds = new List<string> { "1", "2", "3" };
             var subWordIds = new List<string> { "3", "2" };
 
@@ -367,7 +378,6 @@ public void IsInMergeGraylistTest()
         [Test]
         public void IsInMergeGraylistErrorTest()
         {
-            _ = _mergeGraylistRepo.DeleteAllSets(ProjId).Result;
             var wordIds0 = new List<string>();
             var wordIds1 = new List<string> { "1" };
             Assert.That(
diff --git a/Backend/Interfaces/IMergeService.cs b/Backend/Interfaces/IMergeService.cs
index 71e6562588..40beae11b5 100644
--- a/Backend/Interfaces/IMergeService.cs
+++ b/Backend/Interfaces/IMergeService.cs
@@ -10,7 +10,7 @@ public interface IMergeService
         Task<bool> UndoMerge(string projectId, MergeUndoIds ids);
         Task<MergeWordSet> AddToMergeBlacklist(string projectId, string userId, List<string> wordIds);
         Task<MergeWordSet> AddToMergeGraylist(string projectId, string userId, List<string> wordIds);
-        Task<List<string>> RemoveFromMergeGraylist(string projectId, string userId, List<string> wordIds);
+        Task<bool> RemoveFromMergeGraylist(string projectId, string userId, List<string> wordIds);
         Task<bool> IsInMergeBlacklist(string projectId, List<string> wordIds, string? userId = null);
         Task<bool> IsInMergeGraylist(string projectId, List<string> wordIds, string? userId = null);
         Task<int> UpdateMergeBlacklist(string projectId);
diff --git a/Backend/Services/MergeService.cs b/Backend/Services/MergeService.cs
index 9e5903dbd0..01be6ef365 100644
--- a/Backend/Services/MergeService.cs
+++ b/Backend/Services/MergeService.cs
@@ -148,6 +148,7 @@ public async Task<MergeWordSet> AddToMergeBlacklist(
         public async Task<MergeWordSet> AddToMergeGraylist(
             string projectId, string userId, List<string> wordIds)
         {
+            wordIds = wordIds.Distinct().ToList();
             if (wordIds.Count < 2)
             {
                 throw new InvalidMergeWordSetException("Cannot graylist a list of fewer than 2 wordIds.");
@@ -169,27 +170,27 @@ public async Task<MergeWordSet> AddToMergeGraylist(
 
         /// <summary> Remove a List of wordIds from MergeGraylist of specified <see cref="Project"/>. </summary>
         /// <exception cref="InvalidMergeWordSetException"> Throws when wordIds has count less than 2. </exception>
-        /// <returns> List of removed <see cref="MergeWordSet"/> ids. </returns>
-        public async Task<List<string>> RemoveFromMergeGraylist(
+        /// <returns> Boolean indicating whether anything was removed. </returns>
+        public async Task<bool> RemoveFromMergeGraylist(
             string projectId, string userId, List<string> wordIds)
         {
+            wordIds = wordIds.Distinct().ToList();
             if (wordIds.Count < 2)
             {
                 throw new InvalidMergeWordSetException("Cannot have a graylist entry with fewer than 2 wordIds.");
             }
 
-            // Remove all graylist entries fully contained in the input List.
+            // Remove only the set of wordIds, if in graylist (not any subsets)
             var graylist = await _mergeGraylistRepo.GetAllSets(projectId, userId);
-            var removed = new List<string>();
             foreach (var entry in graylist)
             {
-                if (entry.WordIds.All(wordIds.Contains))
+                if (entry.WordIds.All(wordIds.Contains) && wordIds.Count == entry.WordIds.Count)
                 {
                     await _mergeGraylistRepo.Delete(projectId, entry.Id);
-                    removed.Add(entry.Id);
+                    return true;
                 }
             }
-            return removed;
+            return false;
         }
 
         /// <summary> Check if List of wordIds is in MergeBlacklist for specified <see cref="Project"/>. </summary>